Television camera tube cooling arrangements

ABSTRACT

A camera tube cooling arrangement has a body of good thermal conductivity and low dielectric constant mounted in good thermal contact with the face plate of the camera tube and outside the image area of the camera tube. The body is cooled by a thermoelectric cooling unit which is mounted with its cold face in thermal contact with the body and its hot face in thermal contact with a finned heat sink.

O Umted States Patent 1 {111 3,715,491 Finch 1 Feb. 6, 1973 TELEVISIONCAMERA TUBE [56] References Cited COOLING ARRANGEMENTS UNITED STATESPATENTS [75] Inventor: Derek Finch Essex England 3,126,498 3/1964Bendell ..l78/DlG. 14 [73] Assignee: The Marconi Company Limited,

London land Primary Examiner-Robert L. Griffin [22] Filed: March 8, 1971Assistant Examiner-George G. Stellar pp No 121 767 Attorney-Baldwin,Wight & Brown Y 7] ABSTRACT 30 Forei n A lication Priorit Data 1 g pp yA camera tube cooling arrangement has a body of March 1970 Great Brltalngood thermal conductivity and low dielectric constant 52 mounted in goodthermal contact with the face plate US. Cl ..l78/7.2, l78/DIG. 14,33ll33/44, of the camera tube and outside the image area f the [5 1] IntCl H04" camera tube. The body is cooled by a thermo-electric [58] FieidI44 46 cooling unit which is mounted with its cold face in thermalcontact with the body and its hot face in thermal contact with a finnedheat sink.

8 Claims, 1 Drawing Figure SUPPORT =l 6L0CATING DEFLECTION 2 LENS MEANSCOIL CARRIER LENS 17 q 4 QHEAT SINK 3 FOCUSING COIL 7 HEAT TRANSFERPLATE THERMO-ELECTRIC COOLING ELEMENT PATENIEI] n5 s 1975 via 551INVENTOR d} BY KM TTORNEYS TELEVISION CAMERA TUBE COOLING ARRANGEMENTSThis invention relates to television cameras and to television cameratube cooling arrangements therefor.

In some cases it is necessary to operate television camera tubes at aparticular working temperature which is lower than the tubes wouldordinarily attain it may be lower than the surrounding ambienttemperature and with the television cameras in relatively inaccessiblelocations, e.g. at the top of a mast. This necessity may arise, forexample, in the case of Vidicon tubes operated in exposed environmentswhere, unless special means are provided to prevent it, a combination ofhigh ambient temperature, internal heating of the tubes and solarradiation may result in the tubes reaching a temperature at which thereis significantly degraded tube performance. In such cases the provisionof means for cooling the photoconductive layers of the tubes becomesnecessary in practice.

. If the cameras are in readily accessible places, conventional .coolingmethods using vaponcbmpression refrigeration techniques may be employed,a vapor compression unit being used to cool air or another fluid whichin turn is used to cool the camera tube. However, if the tubes are ininaccessible positions it is often inconvenient or even impractical tohave to duct cooled fluid to the tubes. It may also be undesirable tohave a liquid, with consequent risk of leakage, near expensiveelectronic equipment. Moreover the positioning of bulkyvapor-compression units near the tubes is often likely to beinconvenient or impractical.

The present invention seeks to provide improved television camera tubecooling arrangements which may be employed with cameras mountedinaccessible places and which avoid the need to duct a fluid to thecamera tubes.

, According to this invention a camera tube cooling arrangement includesa body of good thermal conductivity and low dielectric constant adaptedto contact with the face plate of the camera tube at a region or regionsoutside the image area thereof; a thermo-electric cooling unit which,when in use, has its cold face thermally connected to said body; andmeans for cooling the hot face of said thermo-electric cooling unit.

By a body of good thermal conductivity is meant a body having athermal'conductivity similar to or approaching that of a metal body. Bya body of low dielectric constant is meant a body having a dielectricconstant and dimensions such that the operation of the camera tube issubstantially unaffected by the presence of said body or by the presenceof a metal or potential on a surface of the body opposite to that whichcontacts with the faceplate of the tube.

Preferably the body of good thermal conductivity and'low dielectricconstant is thermally connected to the thermo electric cooling unit viaa heat transfer plate. A suitable material for the body of good thermalconductivity and low dielectric constant is boron nitride. The metalplate may be made of aluminum.

ries. Suitable elements are, for example, sold under the trade name ofFregistor.

The invention is illustrated in and described by way of example withreference to the accompanying drawing which is a schematic sectionalview of part of a camera tube cooling arrangement in accordance withthis invention. Only parts of the arrangement necessary for a readyunderstanding of the invention are shown. Those parts not shown may beof any convenient and appropriate form.

Referring to the drawing, there is partially shown a camera tube (whichis a Vidicon in the present case) round which are the customarydeflection and focusing coils 2 and 3 respectively, and having a faceplate 4. The cooling arrangement for the tube comprises a body 5 of amaterial having good thermal conductivity and low dielectric constant,such as boron nitride, mounted in good thermal contact with the faceplate 4 by locating means 6. The body 5 is annular and surrounds theuseful image area of the face plate 4. Over the body 5 is an aperturedheat transfer aluminum plate 7, which is in good thermal contacttherewith, and the aperture in which is such that the metal is alloutside the useful image area of the faceplate. A thermo-electriccooling unit comprising a number of thermo electric elements 8 ismounted with the cold face thereof in thermal con- I Preferably meansfor cooling the hot face of the then-Q moelectrie cooling unit is afinned metal plate. A fan is preferably provided'to blow air over thefinned metal plate.

The thermo-electric cooling unit may comprise a plurality of individualthermo-electric cooling elements connected thermally in parallel andelectrically in setact with the aluminum plate 7 and a finned heat sink9 is mounted in good thermal contact with the hot face of the thermoelectric cooling unit. A fan 10 is provided to blow air over the tins ofthe heat sink 9.

A lens 11 is mounted in a lens carrier 12 on a support 13 in front ofthe faceplate 4. i

In operation with a constant voltage applied (by means not shown) acrossthe thermo electric elements reductions in temperature of the hot facesthereof will be accompanied by associated reductions in temperature ofthe cold faces. Thus if the hot faces of the thermo electric elementsrise to temperatures above the ambient air temperature they may becooled by ambient air forced on to the heat-sink 9 by the fan 10 and thetemperatures of the cold faces of the thermo electric elements 8 will becorrespondingly lowered. Accordingly, the metal plate 7, the boronnitride member 5 and the face plate 4 will in turn be cooled.

The signal/noise ratio of the video signal obtained from a Vidicon isdependent on the total value of stray capacity between the tube signalelectrode and earth.

By choosing a material with a suitably high thermal conductivity and asuitably low dielectric constant for the member 5 in contact with theglass faceplate of the Vidicon an efficient transfer of heat with only asmall increase in the stray capacitance of the signal plate electrodemay be achieved. Cooling is therefore obtained without causingsubstantial degradation of the vide /noise ratio.

Cameras with cooling arrangements as illustrated can conveniently beused in inaccessible positions for therefis; no need for ducted coolingfluid; all that is necessary being to provide a small amount ofelectrical power via supply leads for the arrangement.

Iclaim:

1. A camera tube cooling arrangement including a body of goodthermalconductivity and low dielectric 4. An arrangement as claimed inclaim 2 wherein said heat transfer plate is metallic.

5. An arrangement as claimed in claim 4 wherein said heat transfer platecomprises aluminum.

6. An arrangement as claimed in claim 1 wherein the means for coolingthe hot face of the thermoelectric cooling unit is a finned metal plate.

7. An arrangement as claimed in claim 6 wherein a fan is provided toblow air over the finned metal plate.

8. An arrangement as claimed in claim 1 wherein said body comprisesboron nitride.

1. A camera tube cooling arrangement including a body of good thermalconductivity and low dielectric constant in substantially below that ofcopper contact with the face plate of the camera tube at a region orregions outside the image area thereof; a thermo-electric cooling unitwhich, when in use, has its cold face thermally connected to said body;and cooling means for cooling the hot face of said thermo-electriccooling unit.
 1. A camera tube cooling arrangement including a body ofgood thermal conductivity and low dielectric constant in substantiallybelow that of copper contact with the face plate of the camera tube at aregion or regions outside the image area thereof; a thermo-electriccooling unit which, when in use, has its cold face thermally connectedto said body; and cooling means for cooling the hot face of saidthermo-electric cooling unit.
 2. An arrangement as claimed in claim 1wherein the body of good thermal conductivity and low dielectricconstant is thermally connected to the thermo electric cooling unit viaa heat transfer plate.
 3. An arrangement as claimed in claim 2 wheReinthe body of good thermal conductivity and low dielectric constant isboron nitride.
 4. An arrangement as claimed in claim 2 wherein said heattransfer plate is metallic.
 5. An arrangement as claimed in claim 4wherein said heat transfer plate comprises aluminum.
 6. An arrangementas claimed in claim 1 wherein the means for cooling the hot face of thethermoelectric cooling unit is a finned metal plate.
 7. An arrangementas claimed in claim 6 wherein a fan is provided to blow air over thefinned metal plate.